Conventionally, in the finishing construction of plastering mortar on various kinds of buildings such as houses, commercial buildings or underground parking lots, plasterers draw an inkline on the wall of a building and plaster mortar below the inkline along the wall.
However, in remote areas from the wall of a building or on the floor of the building, there is no inkline or criteria of indicating the level of mortar to be put on the floor, and therefore the levelling of the entire floor could not but to rely on the skill or dexterity of plasterers. That is, in conventional constructions using mortar or concrete, levelling the floor of buildings was only dependent on the experience or dexterity of workers, and thus problems were frequently encountered that the surface of the floor was not flat or even, and the floor was partly protruded or caved in.
In this case, an accurate level of mortar on the floor according to a design drawing cannot be obtained, and thus subsequent construction work is required to repair such a defective levelling, which causes the term of construction to be delayed, requires additional building materials such as mortar or concrete, and causes the increase of the costs for materials and the labor costs.
The accurate levelling of the floor of various kinds of buildings has been considerably demanded, but no appropriate devices or instruments have been suggested.
The inventor of the present invention disclosed a device for indicating the level of concrete to keep the floor of buildings flat in prior Korean Utility Model No. 97-109238 as shown in FIG. 1. However, as the device does not comprise a cap in its upper part, problems have been encountered that it is difficult to distinguish the device 100 for indicating the concrete level if excessive concrete were poured on the floor, and on the other hand if concrete were insufficiently supplied, the end of a rod of the device is exposed over the floor of slab.